Ok, here are some suggested revisions ... this is not a script, it's a sketch of a script.
It might be better to ignore all combatmode and setbehaviour stuff, let him sort it out for himself.
You may want to add a line to make the cop get out of his vehicle, although he may do that himself.
#init
_cop = this
not sure how you'll pass the bad guy to the script
globalchat format [ "%1. Suspect spotted. In pursuit.", _cop]
#loop
? not (alive _bad): exit
? _cop knowsabout _bad < 2: exit
? _cop distance _bad < 10: _cop reveal _bad; exit
(you should also have a line here to make the script exit if the cop and/or his vehicle can't move)
_cop doMove getPos _bad
~5
goto "loop"